20+ SoluteLabs Interview Questions and Answers

Data integrity is ensured through ETL testing and loading techniques.

• Perform ETL testing to ensure data accuracy and completeness.

• Use data profiling to identify data quality issues.

• Perform data mapping to ensure correct data transfer.

• Use checksums to verify data integrity.

• Perform data validation to ensure data consistency.

• Use error handling and logging to track and resolve issues.

• Use incremental loading to improve performance and reduce errors.

Explaining the differences between union and union all, having and where, rank and dense rank(), minus and intersection.

• Union combines the result sets of two or more SELECT statements, while Union All returns all rows including duplicates.

• Having is used to filter the results of an aggregate function in a GROUP BY clause, while Where is used to filter rows before grouping.

• Rank assigns a unique rank to each row within a result set, while Dense Rank assigns the same rank to rows...read more

Fact table, dimension table, star schema, and snowflake schema are concepts in data warehousing.

• Fact table contains the measures or metrics of the data warehouse.

• Dimension table contains the attributes or dimensions of the data warehouse.

• Star schema is a type of schema where a fact table is connected to multiple dimension tables.

• Snowflake schema is a type of schema where dimension tables are normalized into multiple related tables.

• These concepts are used to design and organiz...read more

Low, Medium, and High priority defects are categorized based on their impact on the system and urgency of fixing.

• Low priority defects are minor issues that do not significantly impact the system's functionality.

• Medium priority defects are issues that have a noticeable impact on the system but are not critical.

• High priority defects are critical issues that severely impact the system's functionality and need immediate attention.

• Examples: Low priority - Spelling errors, Medium p...read more

Star schema has a single fact table and denormalized dimension tables, while snowflake schema has normalized dimension tables.

• Star schema is simpler and easier to understand, but can lead to data redundancy.

• Snowflake schema is more complex but saves storage space and allows for more flexibility in querying.

• Star schema is better suited for smaller datasets, while snowflake schema is better for larger datasets.

• Example of star schema: sales fact table with denormalized customer ...read more

White box testing is testing the internal structure of the application while black box testing is testing the functionality without knowledge of the internal structure.

• White box testing is also known as clear box testing or structural testing.

• It requires knowledge of the internal workings of the application.

• Examples include unit testing and integration testing.

• Black box testing is also known as functional testing.

• It does not require knowledge of the internal workings of the a...read more

Use OFFSET and FETCH in SQL to retrieve specific records from a table.

• Use OFFSET to skip the first n-1 records

• Use FETCH to limit the number of records to be retrieved

• Example: SELECT * FROM table_name OFFSET 4 ROWS FETCH NEXT 5 ROWS ONLY

SQL query to find second highest salary.

• Use ORDER BY clause in descending order to sort the salaries

• Use LIMIT 1,1 to select the second highest salary

• Example: SELECT salary FROM employees ORDER BY salary DESC LIMIT 1,1

Group by clause is used in SQL to group rows that have the same values into summary rows.

• Group by clause is used with aggregate functions like SUM, COUNT, AVG, etc.

• It is used to group rows based on one or more columns specified in the query.

• Group by clause must be used after the WHERE clause and before the ORDER BY clause.

• Example: SELECT department, COUNT(*) FROM employees GROUP BY department;

Mapping design is the process of creating a mapping between source and target data structures.

• It involves identifying the source and target data structures

• Defining the transformation rules to convert the source data to target data

• Creating a mapping document to document the mapping rules

• Examples include ETL mapping design for data integration projects

A domain name from an email refers to the part after the @ symbol in an email address.

• The domain name is typically the name of the organization or service provider associated with the email address.

• For example, in the email address example@gmail.com, 'gmail.com' is the domain name.

SCD types refer to slowly changing dimensions in data warehousing. Star schema is denormalized while snowflake schema is normalized.

• SCD types refer to how dimensions change over time in a data warehouse

• Type 1: Overwrite existing data with new data

• Type 2: Keep track of historical data with new records

• Type 3: Keep track of some historical data with limited history

• Star schema is denormalized with a central fact table connected to dimension tables

• Snowflake schema is normalized wi...read more

Defect life cycle is the process of identifying, reporting, prioritizing, fixing, and verifying defects in software.

• Defect is identified by testers during testing

• Defect is reported to development team

• Development team prioritizes and fixes the defect

• Fixed defect is verified by testers

• If defect is not fixed, it goes back to development team

• If defect is fixed, it is closed

dense_rank() assigns a unique rank to each distinct row, row_number() assigns a unique sequential integer to each row.

• dense_rank() is used to assign a unique rank to each distinct row based on the specified order.

• row_number() is used to assign a unique sequential integer to each row in the result set.

• Example: dense_rank() - SELECT dense_rank() OVER (ORDER BY salary) AS rank FROM employees;

• Example: row_number() - SELECT row_number() OVER (ORDER BY hire_date) AS row_num FROM em...read more

Use the GROUP BY clause with COUNT() function to find duplicates in SQL.

• Use GROUP BY clause with COUNT() function to group the records by the columns you want to check for duplicates

• Filter the results by using HAVING clause to only show records with count greater than 1

• Example: SELECT column1, column2, COUNT(*) FROM table_name GROUP BY column1, column2 HAVING COUNT(*) > 1;

Constraints are rules or conditions that must be followed in order to ensure data integrity and accuracy.

• Constraints define the limits or restrictions on data values in a database table

• Examples of constraints include primary key, foreign key, unique key, and check constraints

• Constraints help maintain data quality and consistency in a database

Use SQL query with ORDER BY and LIMIT to fetch nth highest salary

• Use ORDER BY salary DESC to sort salaries in descending order

• Use LIMIT n-1,1 to fetch the nth highest salary

• Replace n with the desired position of the salary

Use SQL query with ORDER BY and LIMIT to get 3rd highest salary.

• Use SELECT statement with ORDER BY salary DESC to sort salaries in descending order

• Use LIMIT 1,1 to skip the first two highest salaries and get the third highest salary

Slowly Changing Dimensions (SCD) are used in data warehousing to track changes to data over time. Types include Type 1, Type 2, and Type 3.

• Type 1 SCD: Overwrites old data with new data, losing historical information.

• Type 2 SCD: Creates a new record for each change, preserving historical data.

• Type 3 SCD: Tracks changes by adding columns to the existing record, allowing for limited historical analysis.

SCD Type 2 stands for Slowly Changing Dimension Type 2, which is a data warehousing concept used to track historical changes in data.

• SCD Type 2 maintains historical data by creating new records for changes and preserving old records

• It includes additional columns like start date, end date, and version number to track changes

• Example: If a customer changes their address, a new record is created with the updated address while keeping the old record for historical reference

Joins are used to combine rows from two or more tables based on a related column between them.

• Joins are used in SQL to retrieve data from multiple tables based on a related column.

• Common types of joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.

• Example: SELECT * FROM table1 INNER JOIN table2 ON table1.column = table2.column;

Query to find duplicates in a database table

• Use GROUP BY and HAVING clause to identify duplicate records

• Select columns to check for duplicates

• Use COUNT() function to count occurrences of each unique value

Bug life cycle is the process of a bug from identification to resolution in software testing.

• Bug is identified by tester

• Bug is reported in bug tracking tool

• Bug is assigned to developer

• Developer fixes the bug

• Bug is retested by tester

• Bug is closed if fixed or reopened if not

Test Case is a detailed set of conditions and steps to be followed to validate a particular functionality, while Test Scenario is a high-level description of the functionality to be tested.

• Test Case is detailed and specific, while Test Scenario is high-level and general.

• Test Case includes steps, expected results, and test data, while Test Scenario is more of an overview.

• Test Case is used for detailed testing, while Test Scenario is used for high-level planning.

• Example: Test C...read more

Views in ETL testing are virtual tables that display data from one or more tables based on a query.

• Views are created using SELECT query on one or more tables.

• They do not store data physically, but display data from underlying tables.

• Views can be used to simplify complex queries, restrict access to certain columns, or provide a different perspective on the data.

• Types of views include Simple Views, Complex Views, Materialized Views, and Inline Views.

Use SQL query to fetch the number 3 from a database table.

• Use SELECT statement with WHERE clause to filter for the number 3

• Example: SELECT * FROM table_name WHERE column_name = 3